Containers under pressure, containing compounds such as pastes, foams or glues, find increasing use in the building industry as well as in do-it-yourself (DIY) activities. These containers are usually disposable pressure containers, closed off by a relatively simple valve but which needs to withstand the significant pressures which may occur inside the container.
The containers itself are typically made of metal and are usually cylindrical in shape. The bottom is usually formed by a plate flanged to the cylinder and typically is concave for better withstanding the internal pressure while maintaining the ability for the container to stand upright on a flat surface. The top is usually provided with a container head, also flanged to the cylinder, and which is typically convex for the same reason of higher pressure resistance. A filling opening is usually provided centrally in the cylinder head. When preparing the container for the market, the empty container is typically filled with the compound through this central filling opening in the head, which subsequently may be closed off by flanging the container valve into the filling opening. Many compounds may be filled into the container under atmospheric pressure, and a higher pressure may subsequently be built up or introduced into the container, usually after it is closed off as described. An example wherein pressure builds up after closing the container are the compounds for polyurethane foam, in particular the one-component-foam (OCF), in which, after filling the container, an exothermic chemical reaction between the compounds may be initiated, such as by shaking the container, and the reaction produces heat and builds up pressure by the chemical production and/or the vaporisation of propellants. Propellants for building up the pressure may also be introduced at the moment of filling the container, such as a cold liquid which then is allowed to vaporise after closing the container.
Generally two types of applicators are used in current practice. Occasional and DIY users typically prefer a simple handheld applicator, usually also disposable, which is typically screwed onto the stem of the valve of the container and usually comprises a hose or tube for guiding the flow of the compound to its intended location (also called “a straw”), and a tilting adaptor or lever. The container valves for such handheld applicators comprise a threaded stem onto which the applicator is screwed, and may be referred to as “straw valves”. Such handheld applicators are characterised in that they do not themselves contain a valve for stopping or controlling the flow of compound, but act on the valve provided on the container for those purposes. Consequently, any compound having passed the container valve and entered the handheld applicator is exposed to the atmosphere and, if susceptible, may react further and convert into its ultimate and usually rigid consistency. For these reasons, these adaptors are simple in design and production, cheap, but most often only useable once, and thus disposable. Typically an action on the tilting adaptor or lever provided as part of the handheld applicator results in a tilting of the stem of the container valve, such that one or more openings in the valve stem are set at least partially free into the container contents, thereby opening the straw valve. The assembly is such that the user may hold the container while pushing the lever of the handheld applicator, which provides a rough means for controlling and dosing the compound flow. U.S. Pat. No. 4,165,825 discloses suitable valves for such handheld applications. The compound dosing with such handheld systems is however rather inaccurate, and such a system is therefore more suitable for filling large crevices or cavities, such as those wider than 2 cm.
A variety of handheld applicators are known in the art. All these applicators connect onto the straw valve via a screw connection with the screw thread section which is always provided on the valve stem of a straw valve, and open the valve by tilting the valve stem. They are therefore specific and only suitable for containers equipped with a straw valve. They therefore retain the disadvantage that the dosing of the compound remains difficult to predict and control, e.g. because the position of the side openings at the bottom of the stem is unpredictable with respect to the direction of tilting. These handheld applicators typically only foresee a handle for tilting the valve stem by pushing the handle with the fingers of the hand, and require that the palm of the hand acts on the container itself. The disadvantage with such systems is that during the action of the hand, the connecting attachment between the applicator and the container is strained, and usually in a direction which creates a risk that the attachment would release and create a risk for unintentional release of compound.
The more intensive users, such as professionals or more experienced DIY users, typically prefer a more sophisticated dispensing device, such as a dispensing gun, for applying the compound such as a foam compound. With such dispensing devices, the user holds and manipulates the device or dispensing gun, with the compound container being attached to the gun. Such guns are characterised in that they comprise their own valve, preferably a needle valve for higher accuracy and better closure, for stopping or controlling the flow of compound, and this valve is usually located at the tip of the gun barrel and much more sophisticated than the container valve. It typically allows for a much better control of the compound flow as compared to the container valve. Because the control valve of the gun is located at the tip of the barrel, the compound inside the dispensing gun remains under pressure and sealed from the atmosphere. After use, there remains thus little to no volume of compound which has been exposed to the atmosphere and may react, become rigid and impair the operation of the gun during a subsequent use. Compound inside the gun may only become exposed to the atmosphere for the short time required for exchanging a container on the dispensing gun. This time is usually short, and the dispensing gun is typically used immediately after the exchange, such that the compound inside the dispensing gun is refreshed and after use this new compound remains under pressure and fresh in its fluid state. These dispensing guns are usually more complex and expensive and are typically reused several times after replacing the previous empty container with a fresh and full one. The use of these dispensing guns is more comfortable for the user, and allows a higher accuracy and dosing in the application of the compound than the handheld system. Dispensing guns are therefore also preferred for filling up smaller crevices, such as those smaller than 2 cm wide. The higher dosing accuracy allows working with less excess compound, which usually needs to be removed later and ends up as waste. This reduces the amount of aftercare work required and brings a higher efficiency in material use. Both these advantages are of high interest to the professional or intensive user.
Containers intended for the intensive user are for this purpose conveniently provided in an assembly with a first coupling piece, usually made from a plastic material, which makes the container suitable for attachment to the dispensing gun or dispensing device, and which matches with a connection element integrated in the dispensing gun, or with a second coupling piece which is attached to the dispensing gun, also called a gun adaptor, usually made of metal, such as aluminium or bronze, for making the coupling with the dispensing device or dispensing gun. A suitable foam dispensing gun is for instance disclosed in U.S. Pat. No. 5,271,537, whereby the device comprises a screw connection into which a container may be screwed which has a suitable screw connection, usually by means of a suitable coupling piece on the container. A particularly convenient first coupling piece for such screw connections is disclosed in our co-pending European patent application EP-A-10164924.2, filed 4 Jun. 2010. Instead of a screw connection, the container and the dispensing gun may be connected by means of an even more convenient and safe bayonet type coupling, also called the “Click & Fix” coupling, as described in WO 98/43894. An improved first coupling piece for such Click & Fix coupling is disclosed in our co-pending European patent application EP-A-10164927.5, filed 4 Jun. 2010.
The containers itself, which are intended for the intensive use with a dispensing gun, are closed with a different type of valve, also known as a gun valve in order to differentiate it from the so-called straw valve described above, and which is more suitable for this type of use. The gun valve does not comprise the threaded section which the straw valve requires for screwing the handheld adaptor onto its valve stem. Many gun valves are also not made for being tilted. The gun valve is constructed for, by coupling the container to the gun, being fully opened by pushing the stem of the valve down into the container contents, thereby providing as much opening as possible for a relatively minor movement of the stem. Another difference between the two types of valves is that the straw valve is provided with an extended stem, provided with a screw thread section for screwing on the handheld applicator. This connection between the stem of the straw valve and the corresponding handheld applicator needs to be sufficiently strong such that it allows passing on the force of an action on the handheld applicator such that the straw valve is tilted and thereby opened. Gun valves are not designed for being tilted, and are thus not provided with a stem extension or with a screw thread section. Consequently, straw valve containers cannot be used with equipment designed for gun valve containers. Gun valves are designed for being opened by pushing the stem down into the container, by a movement along the axis of symmetry of the valve stem.
Due to the different valves used for closing off the containers, the container or canister intended for use with the dispensing gun is thus typically different from the container intended for handheld use, i.e. with a handheld applicator. Consequently the supply chain has been carrying two types of containers having different designs, one designed for use with the dispensing gun, i.e. gun valve containers, and the other for use with the handheld applicator, i.e. straw valve containers. Also the handheld applicators are specifically made to work with the straw valve. The screw thread connection is incompatible with gun valves, and the known handheld applicators designed for straw valve containers are unable to operate on a gun valve container.
There has therefore been a need for a handheld applicator which would be suitable for use with the gun valve container, i.e. a container intended for use with the dispensing gun, and which for that purpose has been closed with a gun valve.
WO 2007/112758 discloses a handheld applicator which may be fastened onto the valve stem of a conventional gun valve. The handheld applicator may be “clicked” directly on the valve-stem. By pushing a lever provided as part of the handheld applicator, the valve stem is tilted and the valve is opened. The difficulty with this design is that fastening of the handheld applicator onto or off the valve stem needs to be performed very carefully, as any unintentional tilting of the valve during this operation would cause premature and unintentional spillage of compound, and any damage to the valve may create a safety hazard.
US 2007/0181610 A1 discloses a handheld applicator which is suitable for being snapped onto the flange around a gun valve. In one embodiment, illustrated by FIGS. 3 and 4 in US 2007/0181610 A1, the applicator is provided with a holding ring having a circumferential groove which may be pressed onto the crimping lip of the can dome, i.e. onto the flange which connects the container valve, or more precisely the valve plate thereof, with the container head. This flange connection is formed by shrinking the container valve onto the container head, thereby typically also closing off the container after it has been filled. The disclosed applicator is further provided with a safety plate, preventing an inadvertent opening of the valve until the safety plate is broken off from the applicator. One drawback with this proposal is that the assembly of the applicator with the container provides the same ergonomics of a conventional handheld applicator assembly during use. A further drawback is that removal of the safety plate is irreversible. Once broken off, the security against inadvertent opening cannot be reinstalled. Another drawback is that the handheld applicator of US 2007/0181610 A1 does not comprise a compartment for storing e.g. protecting gloves, useful for the user for protecting his hands against contact with the container content.
WO 2009/147250 discloses another handheld applicator for use with gun valve containers having different dimensions. This applicator is an assembly of at least 3 individual pieces, i.e. the housing, the adapter, a connection piece, and the handle. During operation the adapter displaces vertically and needs to provide a seal with the top of the valve stem. The adapter is described as an interchangeable part, such that with different adapters the applicator may be suitable for different types of valves. The connection piece connects to the nozzle or trunk. During use of the container with the head down, this trunk comes down below the hand of the user. The applicator is provided with a removable safety lip for locking the handle. A drawback of this applicator is that it comprises at least 4 components which need to be produced separately and subsequently require assembly. A further drawback is that it requires an adapter which is suitable for the type of valve it is intended for, and an assembled applicator is only suitable for one type of valve. Another drawback is that the trunk comes out below the hand, which is inconvenient for an accurate aim. A further drawback is that the removal of the safety lip is irreversible. Once broken off, the security against inadvertent opening cannot be reinstalled. Another drawback is that the handheld applicator of WO 2009/147250 does not comprise a compartment for storing an accessory object, e.g. protecting gloves, useful for the user for protecting his hands against contact with the container content.
Handheld applicators for use with gun valve containers are also disclosed in U.S. Pat. No. 5,215,225, U.S. Pat. No. 5,549,226 and WO 2009/004097. These applicators however also suffer from the same disadvantages as the applicator disclosed in US 2007/0181610 A1 and discussed above in more detail.
The containers of the present invention may comprise, under pressure, compounds which are still highly reactive and react out after the compound has been applied into its final location, such as in a crevice or on to a substrate. Contact of the container content with skin, or even more importantly with eyes, is therefore to be avoided. For safety reasons, the container valve and in particular the valve stem should be shielded from being damaged, ripped off or being touched and moved relative to the valve cup. Separate caps have been designed, and the head of coupling pieces snapped on the containers may be provided with caps as seals for the valve compartment. When a gun valve container is not intended for supply with a snapped on coupling piece, but rather with a handheld applicator, sufficient provision should be provided for properly shielding the gun valve from being damaged, ripped off or being touched and moved relative to the valve cup.
There therefore remains a need for a handheld applicator for gun valve containers which provides improved ergonomics over conventional handheld use, offers the dosing and aiming capabilities comparable to those of a dispensing gun, and which may be produced simply and inexpensively as a single product in a single production step. The applicator is preferably provided with a reversible safety seal, more preferably also as an integrated part.
The present invention aims to obviate or at least mitigate the above described problem and/or to provide improvements generally.